This invention relates to a lock for a movable wing, and particularly to a lock intended to be rim fitted to a domestic entrance door.
According to the invention a lock for a wing movable between respective open and closed positions relative to a frame comprises a casing, a bolt operable to extend from the casing or to retract into said casing to a first, normally retracted position, and bolt retention means manually operable at one side of the wing, in use, the bolt retention means being inoperable when said bolt is in its said first, normally retracted position, the bolt being movable in a direction into the casing from its first, normally retracted position, to a second retracted position in which said bolt retention means is operable to a position to retain the bolt retracted.
Preferably said bolt retention means retain the bolt in its first retracted position. More preferably said bolt is releasable from its retention in its first retracted position only by movement of the bolt to its said second retracted position. Desirably said release of the bolt from the bolt retention means is automatic when said retained bolt reaches its second retracted position. Conveniently in said second retracted position, part of said bolt engages a rear wall of the casing.